A method for opening and closing an opening and closing member of a vehicle by using a portable radio transmitter has been developed. For example, JP2005-307692A, which will be hereinafter referred to as Reference 1, discloses an automatic opening and closing system of a power back door (i.e., back door) for a vehicle. In the opening and closing system disclosed in Reference 1, a back door opening and closing operation detection portion is provided at an exterior of a vehicle for detecting a motion of a user related to an opening and closing operation of the back door by the user's hand or arm, for example (i.e., detecting a back door opening and closing operation by the user). In a case where the back door opening and closing operation detection portion detects a predetermined back door opening and closing operation by the user in a state where an ID included in a signal transmitted by a radio transmitter and an ID held by the vehicle match each other, a back door opener is controlled to perform the opening and closing operation of the back door. According to the automatic opening and closing system disclosed in Reference 1, the back door opening and closing operation detection portion is formed by a touch sensor that generates a capacitance when the user touches the sensor and the capacitance that is generated is converted to a pulse signal. Alternatively, the back door opening and closing operation detection portion is formed by a sensor detecting the user's motion in a non-contact manner, for example, by an infrared sensor, an ultrasonic sensor, a heat sensor, or an image recognition system.
In addition, JP2005-133529A, which will be hereinafter referred to as Reference 2, discloses an opening and closing member operation apparatus for a vehicle. In the opening and closing member operation apparatus disclosed in Reference 2, an intentional operation by the user for opening or closing a door is detected by a leg portion detection sensor provided at a lower surface of a vehicle body of the vehicle, for example, at a lower surface of a sill cover or a rear bumper, to thereby open or close the door in a non-contact manner. The leg portion detection sensor is configured to emit radio wave or infrared radiation downwardly of the vehicle to detect in the non-contact manner that the user's leg is placed between the vehicle body and a ground surface as the intentional operation of the user. In a case where the leg portion detection sensor detects the user's leg, for example, in a state where an ID included in a signal transmitted by a radio transmitter and an ID held by the vehicle match each other, an actuator is operated to open or close the door. In the opening and closing member operation apparatus disclosed in Reference 2, the door is inhibited from being opened or closed when the user simply approaches the vehicle, and the door is opened or closed when the user places one's leg intentionally between the ground surface and the lower surface of the vehicle .
In Reference 1, in order to detect the user's motion related to the opening and closing operation in the non-contact manner, the back door opening and closing operation detection portion needs to be a non-contact detection sensor, for example, an infrared sensor, an ultrasonic sensor, an image recognition system, or a heat sensor. In this case, when a non-contact detection distance is specified longer so as to obtain an advantage of the non-contact detection sensor, the back door opening and closing operation may be wrongly performed (i.e., wrong operation of the door) in a state where a person who does not intend to operate the vehicle (the back door) simply passes through near the vehicle.
In Reference 2, the leg portion detection sensor is provided at the lower surface of the vehicle. Thus, it is considered that the aforementioned wrong operation that may be caused in Reference 1 may not occur in a state where a person who does not intend to operate the vehicle simply passes through near the vehicle. Nevertheless, because a detection range of the leg portion detection sensor is defined from the lower surface of the vehicle to the ground surface, a motion of an animal, for example, a cat or a dog that passes through the detection range may be detected. In addition, in a case where a grass or plant, for example, grows within the detection range of the leg portion detection sensor, such grass or plant may be wrongly detected as the user's leg (leg portion) placed into the detection range as the intentional operation of the user. The detection range of the leg portion detection sensor is specified to be a narrow void between the lower surface of the vehicle and the ground surface. Then, an animal may pass through the detection range or a grass or plant may grow from the ground within the detection range. Further, an object that causes reaction of the leg portion detection sensor may be placed within the detection range. In such case, the non-contact detection as a trigger for starting the opening and closing operation of the door may be wrongly conducted. That is, depending on circumstances of the ground at the lower side of the vehicle (for example, animals, grasses or objects causing the sensor to react), the wrong operation of the leg portion detection sensor may occur.
In addition, in Reference 2, the leg portion detection sensor is provided at the lower surface of the vehicle, i.e., at a place that cannot be seen from a side surface of the vehicle, so as not to generate the aforementioned trigger for the opening and closing operation of the door unless the user performs the intentional operation. Thus, Reference 2 produces effects that the opening and closing operation of the door is not initiated unless the user's leg, for example, is purposely placed into the void between the lower surface of the vehicle and the ground surface, and is not initiated in a state where a person who does not intend to operate the door simply approaches the side surface of the vehicle. Nevertheless, in order to produce the aforementioned effects, the leg portion detection sensor is necessarily provided at the lower surface of the vehicle serving as an area that is hidden from the side surface of the vehicle. Thus, in a case where the user who has the intention to operate the door attempts to make the leg portion detection sensor to detect one's leg as the intentional operation for opening or closing the door, it is difficult for the user to directly visually confirm the position of the leg portion detection sensor because the leg portion detection sensor is provided at the portion not to be seen from the side surface of the vehicle. The user may not be able to correctly place one's leg into the detection range of the leg portion detection sensor. In such case, the user needs to seek the detection range which cannot be seen for placing one's leg into the detection range, which may cause the user to feel troublesome.
Regarding the aforementioned issue, in Reference 2, the leg portion detection sensor is provided at a lower side of the position corresponding to the vicinity of a door outer handle that is positioned in the closed state of the slide door, so that the user may recognize the position of the leg portion detection sensor based on the position of the door outer handle. Nevertheless, even though the position or approximate position of the leg portion detection sensor may be indirectly recognized in the aforementioned case, the position of the leg portion detection sensor may not be directly visually confirmed. That is, the door outer handle visually confirmable and serving as an indication of the position of the leg portion detection sensor is physically separated from the actual position of the leg portion detection sensor. Therefore, the user is limited to simply guess or assume the approximate position of the leg portion detection sensor. Because the user is inhibited from directly observing a relative positional relationship between the user's leg as the detection target and an area at which the user assumes that the leg portion detection sensor is positioned, the user may place one's leg repeatedly to the same positions while seeking the detection range of the leg portion detection sensor based on the area at which the leg portion detection sensor is assumed to be positioned. Further, without the visual confirmation, it is difficult for the user to recognize or find an area to which the user's leg has not yet been positioned or placed. The user may feel troublesome while seeking the detection range.
A need thus exists for an automatic opening and closing apparatus of an opening and closing member for a vehicle and a structural member included in a vehicle, which are not susceptible to the drawback mentioned above.